To view the trees at ancestry.com, the viewer has to purchase subscription. I am wondering about RM's online publishing. How does a viewer get access to my online publishing data? I assume by my providing them privately my URL???? Would it be free for him?

It's my understanding, if you have an Ancestry subscription and have a tree on Ancestry, you can invite others to view your tree. They can view as a subscribed member themselves, or can register as a guest to view for free. I haven't delved into this any further, but it sounds like viewees don't necessarily have to buy a subscription simply to view a tree.